Python CLI tool fails with JSON parse error on Rich Panel display

Issue

The CLI tool successfully processed messages through backend services, including FastMCP and vLLM, but encountered a failure during response display. The error occurred due to invalid JSON formatting when attempting to parse the response data, resulting in a crash with a JSON parsing error.

Culprit

The issue stemmed from improper JSON serialization of the backend response data. Specifically:

• The response data was converted to a string using Python’s str() function, which generated a non-JSON-compliant format (e.g., single quotes, Python-specific syntax).
• The CLI tool relied on a JSON parser that expected valid JSON (double quotes, proper syntax) but received a string representation of a Python object, leading to parsing failures.

Solution

Immediate Fix

The string representation of the response data was replaced with proper JSON serialization using json.dumps(), ensuring the output adhered to JSON standards and could be parsed correctly.

Alternative Approaches

1. Pretty Printing: Used alternative display methods, such as pretty printing, for non-JSON data to avoid serialization issues.
2. Debugging: Implemented debugging steps to inspect the data type and content before display, helping to identify and resolve formatting issues early.

Root Cause Prevention

1. Type Checking: Added validation steps to ensure the response data structure is compatible with JSON serialization.
2. Library Updates: Updated the backend client library to guarantee that response data is always JSON-serializable.
3. Error Handling: Introduced robust error handling for serialization failures to gracefully manage unexpected data formats and prevent crashes.

These changes ensured the CLI tool could display backend responses reliably without encountering JSON parsing errors.